Simulation models provide decision support to long-term planning processes. The Bergen Learning Environment for National Development (BLEND) is a game based on a simplified version of Millennium Institute's Threshold 21 model (T21) that sensitizes policy makers in sub-Saharan African nations to the need for simulation-based decision support. The simplification eliminates or aggregates details about individual policy sectors and maintains cross-sector relationships. Validation indicates that the full and the simplified T21 model generate very similar behavior patterns for a wide range of policy scenarios. Pilot tests demonstrate that the simplified T21 model contributes to the learning goals of BLEND. The debriefing employs causal loop diagrams and simulation for structural explanations of the behavior observed during the game. BLEND workshops with repeated runs of the game, full debriefing sessions and different formats of instructional support will contribute further to research on dynamic decision making and learning about tasks with great complexity